Diplomacy of wolves - Holly Lisle

Kait Galweigh is a diplomat ? working to keep the Galweigh Family powerful, honourable and respected. Her particular task is to ensure that the arranged marriage of her flighty cousin, Tippa, is not compromised either by Tippa's own foolishness or by those who would see the Galweigh's fortunes founder.
At a ball in celebration of the New Year and Tippa's marriage into the Dokteerak dynasty, Kait overhears the Paraglese of the Dokteerak and a member of the Sabir clan plotting against her Family. That she can hear the two men at all is thanks to a secret that she has kept hidden in fear of her life. Kait is a shape shifter who in moments of crisis will transform into a wolf. In her life as a diplomat this other self is a blessing and a curse - she can, hear, see and smell with an acuity that show up the lies of politicians and kings, but her curse is that should she ever inadvertently reveal her skill, she will doom herself to a vicious death.